U.S. Major League Soccer has eclipsed both the NBA (National Baskeball Association) and the NHL (National Hockey League) in terms of average attendance at games — a feat that explains why Fox and Telemundo just paid an incredible $1 billion for the rights to broadcast the Word Cup in 2018 and 2022. That price was more than twice what ESPN and Univision paid to broadcast the 2010 and 2014 World Cups.

It also explains why NBC has signed on to broadcast football during primetime next season.

Of course, mere attendance at stadia isn’t the full measure of a sport’s popularity. The indoor arenas of basketball and hockey have structurally smaller audience capacities than the capacious outdoor arenas of football. And percentage attendance at NBA and NHL games tends to be nearer capacity than attendance at soccer. (And then, of course, there’s the unsolved mystery of why “sold out” games at certain clubs seem to feature so many empty seats...)

Nonetheless, it appears that soccer is well on the road to becoming America’s third favorite sport, after throwball American football and baseball. That will have a major impact on sports sponsorship and advertising budgets — providing more media for advertisers to buy and increasing competition between the different sports for sponsor opportunities, such as Adidas’ $200 million pact with MLS.

Here’s how the most recent attendance numbers break down:

NFL: 66,960
MLB: 30,352
MLS: 17,872
NBA: 17,319
NHL: 17,126

MLS has a long way to go to catch baseball and football. Most MLS stadia have a capacity far below their average park gate counts. But look at the growth rate in soccer than the NFL and baseball don’t have: 5.5 million people watched a game of soccer in 2011, up 37 percent from 2010. New teams with new stadiums are planned for Montreal and for a second franchise in New York. Historically, MLS has managed to both increase attendance at individual grounds at the same time as adding entire new grounds.